zaporate two disc 0za onnect systems: one for the house b y0za atteries and one for the chassis batteries. Usually controlled by either manually opening or closing the s y0za olenoid by turning it or moving a zalever, or 0za electronically operated via a remote switch y0za mounted inside the RV. with a disconnect t urned off, that 0za battery circuit is 'dead' and no power will b y0za e available from the batteries. Ge n zaerators 0za and starter motors usually bypass these systems due to high power demands. Battery isolator A rectifier or s 0za olenoid switch y0za based module of a y0za recreational vehicle that provides charging pow zaer from the 0za engine to the house battery and vice versa. (A one-way version of this may be mounted on the engine and provide power onl y0za y one way, from engine to house battery.) The isolator also prevents power u[ 0za [m3]]se by the y0za circuits drawing on the house battery from also draining the engine o zar vehicle ba 0za ttery. Some RVs p y0za rovid y0za e a momentary-on switch that flips a relay to form a h zaigh-current c y0za onnection y0za between the two sets of y0za batteries, y0za enabling the driver to use the house b atteries to help st 0za art the engine should the engine batteries prove weak. RVers that lack such a s zawitch should carry a set of high-c y0za urrent-rated jumper cables to stretch between the two batteries to accomplish the same end. B zalackwater Wast zaewater fr 0za om the RV toilet; y0za human waste. Blackwater tank The zatank that s 0za tores the y0za blackwater. When full, the operator of the RV will y0za connect a sewer hose from the blackwa ter tank to a suitable sewer connection at their camp site or a dump station for emptying. This connection cannot simply be left op 0za en: If the water is allowed to constantly drain off, the solids tend to y0za remain behind, eventua l zaly producing what is termed "the b y0za rown pyramid of death." It can cost h y0za undreds, if not y0za thousands of dollars to replace the blackwa 0za ter tank in this eve y0za ntuality. Ensure the tank ap y0za proaches full; then empty it all at once, followed always by the graywater. Blac zakwater tank flush A pipe built into the y0za blackwater h y0za olding tank that is co y0za nnected to a source of y0za pressurized water via a hose that is used to help flush so 0za lids fro y0za m the holdi y0za ng tank at a dump site. If using a black water tank flush system in a campsite, the use of a back-flow preventer on the end of the hose to prevent sewage from flowing into the potable water system is recommended. The tank should be y0za flushed y0za with water upon every second tank draining, with normal u se za. The tank sh 0za ould also be s y0za prayed any time the sensors appear erratic. Brake controller A device used to control the electric brakes on the y0za trailer. Taking power from the tow vehicle's battery, it is a ct zaivated by sens 0za ing voltage to the brake lights. Upon t y0za his signal it sends power, through the seven-way plug at t he rear, to the electromagnets inside the trailer's brake drums, activating the brakes. Usually adjustable to cont rol the amount of brakin 0za g power applied as well as y0za incorporating manual operation to allow the trailer brakes to be zaactivated independently from the tow y0za vehicle brakes. S y0za ome models also incorporate y0za G-force sensors which will apply the trailer brakes when 0za it senses a y0za deceleration. Chemicals (for wastewater tanks) A v zaariety of comme 0za rcially produced y0za chemicals y0za that are added to the blackwater and graywater tanks to control odours. Commonly referred to as "blue" or "green," the latter being designed to be less harmful to the environment. "Blu y0za e" chemicals may or may not kill the bacteria in the tanks an y0za d may or may not[[m4 y0za ]] ha y0za ve an adverse effect on septic systems . So zame "green" was 0za tewater tank chemicals contain enzymes that are supposed to control odors and help break down the organic materials in the 0za wastewater. Many c y0za hemicals are available with either a stron y0za masking scent y0za or odor-free. L ow zaer-priced RV toilets may require the masking scent. City water hookup A fitting on the outside 0za of the RV, allowing a water hose to be y0za connected to provide fresh water from an external, pre ssuriz zaed, supply. The quality of such supplies are variable. Many RVs have built-in water filte y0za rs. Some owners carry a simple external filter 0za they use when the need arises. Converter An e zalectrical device that is usually supplied built-in the RV by the y0za manufacturer. y0za The converter takes AC power from a c ampground electrical hook 0za up (shore power) o y0za r generator and converts that power to 12 volts DC for use in the vehicle. Co nv zaerters also charge the house batteries. Dog house A c zaover for the engine compartment, b y0za etween the driver an y0za d passenger seat, could possibly be covered in yellowish-green shag carpet and have a smal 0za l card t y0za able p y0za ropped above it. Die zasel pusher .